| 摘要 |
The invention relates to a method and a device for optimization of electric fields in measurement cells of Fourier transform ion cyclotron resonance mass spectrometers. The invention is based on the rationale that asymmetric electric fields with uniformly or non-uniformly perturbed field axes can appear in ion cyclotron resonance cells and therefore the axis of the magnetron orbit can become radially displaced. Shifted magnetron orbits negatively affect the cyclotron excitation, deteriorate the FT-ICR signal, increase the intensity of an even-numbered harmonics peak, lead to stronger side bands of the FT-ICR signal, and in extreme cases, cause loss of ions. The present invention helps in probing the shift of the magnetron motion, detecting parameters indicative of the offset of the electric field axis and/or correcting it by trimming it back to the geometric axis of the cell. |
| 主权项 |
1. A method for detecting an asymmetry of an electric field in an FT-ICR cell in a radial direction relative to an axis of the FT-ICR cell,
wherein parameters indicative of a position or a diameter of a center axis of a magnetron motion for an ion with a reduced cyclotron frequency vR in the ICR cell are determined by monitoring relative intensities of at least one of the ion signals with frequencies of nvR and (nvR±mvM), vM being a magnetron frequency, n=2, 4, 6, . . . , and m=1, 2, 3, . . . , as a function of the ion's post capture delay time, and by evaluating maxima and minima of the relative intensities. |
